1. Field of Invention
The present invention relates to a manual transmission for vehicles. More particularly, the present invention relates to a manual transmission for vehicles that minimizes rotational inertia and improves rattle as a consequence of preventing unnecessary idling of a first speed gear and a reverse speed gear by maintaining a first input gear to be a free gear state at all shift-speeds except a first forward speed and a reverse speed.
2. Description of Related Art
Generally, vibration is generated by impact when teeth of free gears disposed on rotation shafts freely bumps into driving gears fixedly disposed on the rotation shafts. A rattle in a manual transmission for vehicles means that the vibration generated by the impact is transmitted to the rotation shafts, bearings, and a transmission case and noise occurs.
If load is not applied to a free gear FG, teeth of the free gear FG is not engaged with both teeth of a driving gear DG as shown in FIG. 1. At this state, if load (exciting force of an engine) is applied to the free gear FG, the free gear FG moves easily and the teeth of the free gear FG bumps into the teeth of the driving gear DG. Therefore, double side impact occurs, and thereby the rattle occurs.
When the rattle occurs, the double side impact which the free gear FG applies to the rotation shaft is proportional to rotational inertia of the free gear FG, and rattle sensitivity is proportional to total rotational inertia of the free gears.
Gear arrangement of a conventional manual transmission will be described. As shown in FIG. 2, gears that are related to each shift-speed are disposed on an input shaft PIS and an output shaft POS disposed in parallel with the input shaft PIS with a predetermined distance.
A first input gear GI1, a second input gear GI2, a first synchronizer mechanism PSYN1 including third and fourth input gears GI3 and GI4, and a second synchronizer mechanism PSYN2 including fifth and sixth input gears GI5 and GI6 are sequentially disposed on the input shaft PIS from a front side to a rear side.
Herein, the front side means a side close to an engine and the rear side means a side that is far from the engine.
The first input gear GI1 and the second input gear GI2 are integrally formed with the input shaft PIS so as to rotate together with the input shaft PIS when the input shaft PIS rotates.
In addition, the third, fourth, fifth, and sixth input gears GI3, GI4, GI5, and GI6 are disposed such that rotations of the third, fourth, fifth, and sixth input gears GI3, GI4, GI5, and GI6 are not directly affected by rotation of the input shaft IS (that is, free gear), and each input gear GI3, GI4, GI5, and GI6 rotates together with the input shaft PIS through selective engagement with sleeves PS1 and PS2.
In addition, a first output gear POG1, a third synchronizer mechanism PSYN3 having first and second speed gears GO1 and GO2 engaged respectively to the first and second input gears GI1 and GI2, and third, fourth, fifth, and sixth speed gears GO3, GO4, GO5, and GO6 engaged respectively to the third, fourth, fifth, and sixth input gears GI3, GI4, GI5, and GI6 are disposed on the output shaft POS.
The first and second speed gears GO1 and GO2 are disposed such that rotations of the first and second speed gears GO1 and GO2 do not directly affect on rotation of the output shaft POS (that is, free gear), and rotate together with the output shaft POS through selective engagement with a sleeve PS3. The third, fourth, fifth, and sixth speed gears GO3, GO4, GO5, and GO6 are integrally formed with the output shaft POS.
In addition, a second output gear POG2 and a fourth synchronizer mechanism PSYN4 having a reverse speed gear PRG engaged to the first speed gear GO1 are disposed on a reverse speed output shaft PRS disposed in parallel with the input shaft PIS.
The reverse speed gear PRG is disposed such that rotation of the reverse speed gear PRG does not directly affect on rotation of the reverse speed output shaft PRS, and rotates together with the reverse speed output shaft PRS through selective engagement with a sleeve PS4.
In addition, the first and second output gears POG1 and POG2, as shown in FIG. 3, are engaged to driven gear PDG of a differential so as to output converted torque.
Since the first, second, third, and fourth synchronizer mechanisms PSYN1, PSYN2, PSYN3, and PSYN4 are the same as or similar to a conventional synchronizer mechanism applied to a conventional manual transmission, detailed description thereof will be omitted. In addition, each sleeve PS1, PS2, PS3, and PS4 of the first, second, third, and fourth synchronizer mechanisms PSYN1 PSYN2, PSYN3, and PSYN4, as well known to a person of skilled in the art, is operated by a shift fork that is operated by a shift lever disposed at a driver's seat.
Since the reverse speed gear PRG is always engaged with the first speed gear GO1 and the first speed gear GO1 is always engaged with the first input gear GI1 in the manual transmission as shown in FIG. 3, the reverse speed gear PRG and the first speed gear GO1 are idling at shift-speeds other than a first forward speed and a reverse speed and rattle occurs if the input shaft PIS rotates.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.